diff --git a/src/config/config.go b/src/config/config.go
index 47961bf2..08a2454e 100644
--- a/src/config/config.go
+++ b/src/config/config.go
@@ -45,6 +45,7 @@ const (
 	NonInteractiveCommandsPluginName = "NonInteractiveCommands"
 
 	//Agent Versions
-	TerminateSessionFlagSupportedAfterThisAgentVersion = "2.3.722.0"
-	TCPMultiplexingSupportedAfterThisAgentVersion      = "3.0.196.0"
+	TerminateSessionFlagSupportedAfterThisAgentVersion            = "2.3.722.0"
+	TCPMultiplexingSupportedAfterThisAgentVersion                 = "3.0.196.0"
+	TCPMultiplexingWithSmuxKeepAliveDisabledAfterThisAgentVersion = "3.1.1511.0"
 )
diff --git a/src/sessionmanagerplugin/session/portsession/basicportforwarding.go b/src/sessionmanagerplugin/session/portsession/basicportforwarding.go
index 95b91d81..28c0f2d2 100644
--- a/src/sessionmanagerplugin/session/portsession/basicportforwarding.go
+++ b/src/sessionmanagerplugin/session/portsession/basicportforwarding.go
@@ -65,7 +65,7 @@ func (p *BasicPortForwarding) Stop() {
 }
 
 // InitializeStreams establishes connection and initializes the stream
-func (p *BasicPortForwarding) InitializeStreams(log log.T) (err error) {
+func (p *BasicPortForwarding) InitializeStreams(log log.T, agentVersion string) (err error) {
 	p.handleControlSignals(log)
 	if err = p.startLocalConn(log); err != nil {
 		return
diff --git a/src/sessionmanagerplugin/session/portsession/muxportforwarding.go b/src/sessionmanagerplugin/session/portsession/muxportforwarding.go
index f5a03372..209bf234 100644
--- a/src/sessionmanagerplugin/session/portsession/muxportforwarding.go
+++ b/src/sessionmanagerplugin/session/portsession/muxportforwarding.go
@@ -34,6 +34,7 @@ import (
 	"github.com/aws/SSMCLI/src/message"
 	"github.com/aws/SSMCLI/src/sessionmanagerplugin/session"
 	"github.com/aws/SSMCLI/src/sessionmanagerplugin/session/sessionutil"
+	"github.com/aws/SSMCLI/src/version"
 	"github.com/xtaci/smux"
 	"golang.org/x/sync/errgroup"
 )
@@ -90,12 +91,12 @@ func (p *MuxPortForwarding) Stop() {
 }
 
 // InitializeStreams initializes i/o streams
-func (p *MuxPortForwarding) InitializeStreams(log log.T) (err error) {
+func (p *MuxPortForwarding) InitializeStreams(log log.T, agentVersion string) (err error) {
 
 	p.handleControlSignals(log)
 	p.socketFile = getUnixSocketPath(p.sessionId, os.TempDir(), "session_manager_plugin_mux.sock")
 
-	if err = p.initialize(log); err != nil {
+	if err = p.initialize(log, agentVersion); err != nil {
 		p.cleanUp()
 	}
 	return
@@ -142,7 +143,7 @@ func (p *MuxPortForwarding) cleanUp() {
 }
 
 // initialize opens a network connection that acts as smux client
-func (p *MuxPortForwarding) initialize(log log.T) (err error) {
+func (p *MuxPortForwarding) initialize(log log.T, agentVersion string) (err error) {
 
 	// open a network listener
 	var listener net.Listener
@@ -165,10 +166,17 @@ func (p *MuxPortForwarding) initialize(log log.T) (err error) {
 	g.Go(func() error {
 		if muxConn, err := net.Dial(listener.Addr().Network(), listener.Addr().String()); err != nil {
 			return err
-		} else if muxSession, err := smux.Client(muxConn, nil); err != nil {
-			return err
 		} else {
-			p.muxClient = &MuxClient{muxConn, muxSession}
+			smuxConfig := smux.DefaultConfig()
+			if version.DoesAgentSupportDisableSmuxKeepAlive(log, agentVersion) {
+				// Disable smux KeepAlive or else it breaks Session Manager idle timeout.
+				smuxConfig.KeepAliveDisabled = true
+			}
+			if muxSession, err := smux.Client(muxConn, smuxConfig); err != nil {
+				return err
+			} else {
+				p.muxClient = &MuxClient{muxConn, muxSession}
+			}
 		}
 		return nil
 	})
diff --git a/src/sessionmanagerplugin/session/portsession/portsession.go b/src/sessionmanagerplugin/session/portsession/portsession.go
index b2d6450a..a2b95cb9 100644
--- a/src/sessionmanagerplugin/session/portsession/portsession.go
+++ b/src/sessionmanagerplugin/session/portsession/portsession.go
@@ -35,7 +35,7 @@ type PortSession struct {
 
 type IPortSession interface {
 	IsStreamNotSet() (status bool)
-	InitializeStreams(log log.T) (err error)
+	InitializeStreams(log log.T, agentVersion string) (err error)
 	ReadStream(log log.T) (err error)
 	WriteStream(outputMessage message.ClientMessage) (err error)
 	Stop()
@@ -111,7 +111,7 @@ func (s *PortSession) Stop() {
 
 // StartSession redirects inputStream/outputStream data to datachannel.
 func (s *PortSession) SetSessionHandlers(log log.T) (err error) {
-	if err = s.portSessionType.InitializeStreams(log); err != nil {
+	if err = s.portSessionType.InitializeStreams(log, s.DataChannel.GetAgentVersion()); err != nil {
 		return err
 	}
 
diff --git a/src/sessionmanagerplugin/session/portsession/standardstreamforwarding.go b/src/sessionmanagerplugin/session/portsession/standardstreamforwarding.go
index f61278fe..52e5da50 100644
--- a/src/sessionmanagerplugin/session/portsession/standardstreamforwarding.go
+++ b/src/sessionmanagerplugin/session/portsession/standardstreamforwarding.go
@@ -46,7 +46,7 @@ func (p *StandardStreamForwarding) Stop() {
 }
 
 // InitializeStreams initializes the streams with its file descriptors
-func (p *StandardStreamForwarding) InitializeStreams(log log.T) (err error) {
+func (p *StandardStreamForwarding) InitializeStreams(log log.T, agentVersion string) (err error) {
 	p.inputStream = os.Stdin
 	p.outputStream = os.Stdout
 	return
diff --git a/src/version/versionvalidator.go b/src/version/versionvalidator.go
index ea3c9a02..6f3f4b52 100644
--- a/src/version/versionvalidator.go
+++ b/src/version/versionvalidator.go
@@ -24,6 +24,11 @@ func DoesAgentSupportTCPMultiplexing(log log.T, agentVersion string) (supported
 	return isAgentVersionGreaterThanSupportedVersion(log, agentVersion, config.TCPMultiplexingSupportedAfterThisAgentVersion)
 }
 
+// DoesAgentSupportDisableSmuxKeepAlive returns true if given agentVersion disables smux KeepAlive in TCP multiplexing in port plugin, false otherwise
+func DoesAgentSupportDisableSmuxKeepAlive(log log.T, agentVersion string) (supported bool) {
+	return isAgentVersionGreaterThanSupportedVersion(log, agentVersion, config.TCPMultiplexingWithSmuxKeepAliveDisabledAfterThisAgentVersion)
+}
+
 // DoesAgentSupportTerminateSessionFlag returns true if given agentVersion supports TerminateSession flag, false otherwise
 func DoesAgentSupportTerminateSessionFlag(log log.T, agentVersion string) (supported bool) {
 	return isAgentVersionGreaterThanSupportedVersion(log, agentVersion, config.TerminateSessionFlagSupportedAfterThisAgentVersion)
diff --git a/src/version/versionvalidator_test.go b/src/version/versionvalidator_test.go
index 7ef12e83..471e8b46 100644
--- a/src/version/versionvalidator_test.go
+++ b/src/version/versionvalidator_test.go
@@ -148,3 +148,11 @@ func TestDoesAgentSupportTerminateSessionFlagForNotSupportedScenario(t *testing.
 func TestDoesAgentSupportTerminateSessionFlagWhenAgentVersionIsEqualSupportedAfterVersion(t *testing.T) {
 	assert.False(t, DoesAgentSupportTerminateSessionFlag(mockLog, "2.3.722.0"))
 }
+
+func TestDoesAgentSupportDisableSmuxKeepAliveForNotSupportedScenario(t *testing.T) {
+	assert.False(t, DoesAgentSupportDisableSmuxKeepAlive(mockLog, "3.1.1476.0"))
+}
+
+func TestDoesAgentSupportDisableSmuxKeepAliveForSupportedScenario(t *testing.T) {
+	assert.True(t, DoesAgentSupportDisableSmuxKeepAlive(mockLog, "3.1.1600.0"))
+}